Tool driving mechanism



Feb. 19, 1935. E. J. LEES 1,991,754

' l TOOL DRIVING MECHANISM Filed June 19,1930 4 Sheets-Sheet 1 Feb. 19, 1935.

E. J. LEES TOOL DRIVING MECHANISM Filed- June 19, 1930 4 Sheets-Sheet 2 HIIIIIIHIIIII gwwntoc M J4ea Feb. 19, 1935. E, J, g 1,991,754

TOOL DRIVING MECHANISM Filed June 19, 1950 4 Sheets-Sheet 5 Feb. 19, 1935. E. J. LEES TOOL DRIVING MECHANISM 4 Sheets-Sheet 4 Filed June 19, 1930 Jwbmtoz Patented Feb. 19, 1935 PATENT. OFFICE TOOL DRIVING NIECHANISM Ernest J. Lees, Cleveland, Ohio, assignor to The Lees-Bradner Company, Cleveland, Ohio, a corporation of Ohio Application June 19, 1930, Serial No. 462,260

vs Claims. (01. 90-45 V This invention relates to a tool driving mechanism for cutters, grinding apparatus, and the like.

An object of the invention is to provide a driving'mechanism which will be simple in construction and-by which a plurality of cutting speeds maybe-obtained. I -Another-zobject; is to provide means for elimina-ting undesired vibrations from the cutting tool or element. v

Other objects will hereinafter appear.

The invention will the-better understood from the description of one practical embodiment thereof illustrated in the accompanying drawings, which;-

Figure l-is a front; elevation of the head and associated parts of a thread milling machine embodying the invention;

Figure 2 is asside-elevational'view thereof;

Figure 3 is-a sectional :view taken on the'line of Ffigureil, parts being broken away;

Figure 4: is ;a:fragmentary sectionalview taken on the;line1V--IV;of Figure'3; and

Figure v.5 is a sectional view taken on the line V-'-V of *FigureA.

in Figure ilxthesbed of a thread miller is indicated :at .1, ;this .being provided on its upper surface with ways2 on which are mounted a head stock- (not shown) a .footstock '3, and thefhead abovesreferred to. 'I'hisheadconsists of abase 4iadjus'table along the ways i 2, which carries .two :trunnion rings 5. and 6, "in which the tooloperating mechanism is supported.

This mechanism consists ofeahousing indicated .generallyat '7 arranged to be rotated in the trun- .-nion rings .,by;a worm engaging a worm wheel 7a formed .in .the exterior of. thehousing and in which housing :is .journalled a shaft :8 coaxial withthertrunnion rings. :Splined .to the shaft is aagear Q' meshing with and driven .by a gear 10 splined tothedrive-shaft ill of the machine. The --shaft 8 drives, through gearing to be hereinafter 1 described,a tool spindle 12 carrying a cutter 13 "or a grindi-ng'wheel, or the like, which operates upon the work.

The shaft 8 has keyed toit a sleeve l4v arranged tobe moved axially of theshaft by a hand lever 15, carried by a vertical shaft 16, the shaft-being provided with an .arml'? ending in ca bifurcated end 18 by which it engages pins 20 .upon a yoke. 21 carried in a groove in and adjacent .the-o-end-of thesleeve. Fixed tothe sleeve are two pinions ,22 and 23. A bushing .24 surrounds the .sleeve and servesv as onebearing for theshaft 8,

while the end of the shaft is supported in a bearing 25 within thehousing.

A shaft 26 is supported by bearings 27 and 28 within the housing parallel to shaft 8. Attached to this shaft, as by screws 29, is a cylindrical member .30 having formed on its exterior two gears 31 and 32, the former of which is arranged to mesh with pinion 22, when this is moved to its rearmost position, and the latter of which meshes with pinion 23 when the sleeve is moved .to its extreme forwardposition, the gears 31 and32 being spaced apart sufliciently to clearbothpinions when the sleeve isat its intermediate position as shown in full lines in Figure 3.

From the above, it will be seen that twospeeds may be obtained, one by causing pinion 22 to mesh with gear 31, and the otherbycausing pinion 23 to mesh withgear 32. V r f The shaft 26has formed upon it-a bevelled pinion 33 which meshes with a bevelledgear 34 upona shaft 35 supportedin bearings 36 and 37. This-shaft has its axis in a plane normal to the .axisof shaft-8 and has cut up upon it a pinion 38. The pinion 38, in turn, meshes with an idler gear 39 carried by a shaft 40 journalled in-the housing, which, in turn, meshes withanddrives a pinion 41 formed in the tool spindle 12.

The tool spindle is carried in bearings 42, 43 and 44, the firsttwo of which are supported in a block 45'secured within a recess 46 in the front of the head, as by screws 47, and the latter of which is supported by a yoke 48, also attached by screws to the head.

From the preceding description, it will be apparent that the block and yoke may be readily 2 5 removed from the face of the machine, and re- .placed by others carrying spindles having pinions provided with different numbers of teeth,

and that numerous variations in the speed of the tool may be effected by substituting different spin- 4 dles together with their supporting blocks and yokes for those shown.

Obviously in the different blocks, it will be necessary to support the spindles so that the idler is formed witha hub 49 upon which is rotatably mounted a narrow gear-shaped plate 50, the teeth of which engage those of pinion 41, but clear pinion 38 and shaft 35.

The plate is provided with recessed bosses 51 in which are positioned compression springs 52 upon the outer ends of which a plate or washer 53 is arranged to bear, this being pressed upon the springs by a nut 54; threaded on hub 49.

The plate 50 has a different number of teeth than the idler 39, conveniently one more or one less. These teeth are designed to mesh with those on pinion 41 at a different pressure angle than those of the idler, so that the pitch circles of the idler and pinion differ from those of the plate and pinion, to make it possible to maintain the pinion in mesh with both the idler and plate, both of the latter being. coaxial but rotating at slightly different speeds. If, for instance, there are fifty teeth on the idler and forty nine on the pinion, it will be obvious that when the idler has made one revolution, the plate will have made 1-1 /49 revolutions. To do this, it must slide upon the idler, and this sliding is resisted by friction between the parts, the friction being proportionate to the pressure on springs 52, and so controlled by the adjustment of nut 54.

As each successive tooth of the plate comes into contact with a tooth of the pinion 41, it is arranged in slightly staggered relation to the corresponding tooth of the idler, the aggregate distance across the tooth of the plate-and that of the idler being slightly greater than the space between successive teeth of pinion 41, and so the tooth of the plate must be pressed into alinement with that of the idler, causing the plate to slide upon the idler, in the instance above referred to, 1/49th of the width of one tooth.

The frictional resistance to this sliding causes,

at all times, the exertion of a considerable force upon adjacent sides of successive teeth on pinion 41, preventing anybacklash, and it is found that this resistance eliminates any tendency to chattering or other undesirable vibrations.

By having the speed reduction gearing closely adjacent the spindle 12, the shaft 8 and gears 9 and 10 transmit power to the head at relatively high speeds, and with low stresses, so that no appreciable springing or distortion exists, while at the parts of the gear train where'speeds become lower and stresses higher, the parts are short and rigidly supported by the housing.

Experimentation has shown thateven if there is considerable backlash or looseness of'the parts farther back in the gear train than the idler, these are not communicated to the spindle, but that its operation is rendered smooth" and continuous by the drive described.

I While I have described the illustrated embodiment of my invention in some particularity, obviously many other embodiments will readily occur to those skilled in this art, and I, therefore, do not limit myself to the precise details shown and described herein, but claim as my invention all embodiments, variations and modifications coming within the scope of the subjoined claims.

I claim:

1. A tool operating mechanism comprising a drive shaft connected to a source of power, a casing arranged in bearings adjacent its ends in which it may be rotated, a shaft coaxial-with said bearings extending into said casing, and driven by said drive shaft, a gear train within the casing operated by said last mentioned shaft, a tool spindle carried by the casing and rotated by said gear train, and frictional means resisting the turning of said spindle.

2. In a machine tool, a head, spaced bearings supporting the head and adjacent each end thereof a cutter spindle journalled therein with its axis normal to that of the pivotal support, a drive shaft external to said head, a shaft extending into said head, gearing between said drive shaft and said second mentioned shaft, a plurality of gears carried by the second mentioned shaft, a back shaft in the head, a plurality of. gears carried by said back shaft selectively engageable with said gears carried by the second mentioned shaft, and gearing between said back shaft'and spindle.

3. In a machine tool, a head comprising 9. casing, the exterior of the casing having formed thereon adjacent its ends trunnion-like bearing surfaces, 2. pair of spaced bearings supporting said bearing surfaces, a shaft coaxial with said trunnions extending from the exterior to the interior of said casing and journalled therein, means external the casing for rotating said shaft, a sleeve splined to said shaft and carrying a plurality of gears, a back shaft journalledin saidcasing parallel to said first mentioned shaft, and provided with a plurality of gears with which those on the sleeve may be selectively engaged, a bevelled pinion on said back shaft, a. shaft carrying at one end a bevelled gear meshing with said bevelled pinion, a gear upon said shaft, an idler meshing with said last mentioned gear, and a tool spindle formed with a pinion meshing with said idler. v

4. In a machine tool, a head comprising a casing, the exterior of the casing having formed thereon adjacent its ends trunnion-like bearing surfaces, a pair of spaced bearings supporting said bearing surfaces, a shaft coaxial with said trunnions extending from the exterior to the interior of said casing and journalled therein, means external the casing for rotating said shaft, a sleeve splined to said shaft, and carrying a. plurality of gears, a back shaft joumalled in said casing parallel to said first mentioned shaft, and provided with a plurality of gears with which those on the sleeve may be selectively engaged, a bevelled pinion on said back shaft, a shaft carrying at one end a bevelled gear meshing with saidlast mentioned gear, a tool spindle formed with apinion meshing with said idler, said tool spindle having its axis normal to that of the first mentioned shaft.

5. In a machine tool, a head comprising a casing, the exterior of the casing having formed thereon adjacent its ends trunnion-like bearing surfaces, a pair of spaced bearings supporting said bearing surfaces, ashaft coaxial with said trunnions extending from the exterior to the interior of the casing, driving means on the exterior of the casingconnected to the shaft, gearing within the casing, a block detachably secured in a recess in the front face of the casing, a tool spindle journalled in said block, and a gear on v said spindle driven by said gear train.

6. Ina machine tool, a head comprising a casing, the exterior of the casing having formed thereonfadjacent its ends trunnion-like bearing surfaces, a pair of spaced bearings supporting said bearing' surfaces, a shaft coaxial with said in a recess in the face thereof, each block having journalled in it a tool spindle, the tool spindles being provided with pinions of different numbers of teeth, any of which mesh with the last gear of said gear train. I

7. In a machine tool, a cutter carrying head comprising a casing, the exterior of the casing having formed thereon adjacent its ends trunnion-like bearing surfaces, a pair of spaced bearings supporting said bearing surfaces, a shaft coaxial with said trunnions passing from the exterior to the interior of said casing, driving means for said shaft on the exterior of said casing, reduction gearing within the casing operated by said shaft, an idler journalled in the casing with its axis lying in a plane normal to the axis of said shaft, a recess in the front of said casing exposing a portion of the idler, a block detachably secured in said recess and having a tool spindle journalled therein, the spindle being provided with a pinion arranged to mesh with said idler when the block is secured in the recess.

8. In a machine tool, a cutter carrying head comprising a casing, the exterior of the casing having formed thereon adjacent its ends trunnion-like bearing surfaces, a pair of spaced bearings supporting said bearing surfaces, a shaft coaxial with said trunnions passing from the exterior to the interior of said casing, driving means for said shaft on the exterior of said casing, reduction gearing within the casing operated by said shaft, an idler journalled in the casing with its axis lying in a plane normal to the axis of said shaft, a second idler coaxial with the first mentioned idler having the same diameter and a different number of teeth therefrom, friction means between said idlers, a recess in the front of said casing exposing a portion of the idlers, a block detachably secured in said recess and having a tool spindle journalled therein, the spindle being provided with a pinion arranged to mesh with both said idlers when the block is secured in the recess.

ERNEST J. LEES. 

